We have a 1930 cabin in upstate NY. The property has a creek in front and small waterfall in back. The original owners built the back out abutting a large rock formation. The back floor appears to have been laid directly over rock. Now, we are seeing moisture coming thru the floor boards and what appears to be wood rot in some areas. We are panicking. What should we do to rectify this—long term? Short term?We do not live there year round.